1. Field of the Invention
The present invention relates to a stereophonic microphone system for improving stereophonic reproduction. The microphone system utilizes interaural intensity stereophonic and/or time difference stereophonic pickup methods.
2. Description of the Related Art
Stereophonic recording methods using interaural intensity and/or time difference stereophony are known. However, the reproduction takes place generally only by using loudspeakers in basic stereo placement or by means of headsets. These types of reproduction have the disadvantages of space-related stereophony.
Among these pickup methods are the XY-method using two cardioid microphones which are placed closely next to each other at an angle of 90.degree. to 135.degree.; the MS-method using a cardioid microphone and a bidirectional microphone arranged at a right angle to the cardioid microphone; the AB-method with two pressure pickups spaced apart 20 to 330 cm for obtaining the effect of arrival time differences; the ORTF-method with two cardioids spaced approximately 17.5 cm from each other and at an angle of 100.degree. to 140.degree.; the OSS-method according to Jecklin with a separation disk and pressure pickups arranged in front of both sides; and the dummy head method utilizing replicas of the human head with the ears.
None of the known pickup methods was capable of meeting the requirements for compatibility of loudspeaker and headset reproduction. Also, a spatial impression which would come close to that of natural hearing, for example, in a concert hall, has never been achieved. In the case of loudspeaker reproduction, the hearing illusion remains in the plane of the loudspeaker laterally limited by the area between the loudspeakers or raised above the connecting line of the loudspeakers. The headset reproduction suffers from the localization in the head or at least a hearing illusion created near the ear. Although an artificially created reverberation simulates some spatial effect, however, this effect is not comparable to the hearing event in a concert hall.
With the exception of the dummy head technology, ear resonances are not created during sound pickup as well as during reproduction in accordance with the interaural intensity and/or time difference methods. The resonances generated at the ears of the listener by means of the loudspeakers in basic stereo placement are limited to the direction of incidence of each loudspeaker and serve merely as a localization stimulation of the location-determining reproducing transducers (the loudspeakers). In the case of a loudspeaker reproduction in a room, the reflections from the walls generate ear resonances from all directions of incidence, however, these reflections are only perceived as reverberations. In the case of reproduction by means of headsets, only ear resonances with proximity effects are created because of the structural design of headsets, particularly due to the orientation of the diaphragm, even if no reflections occur due to the small coupling space and the acoustically stiff components of the transducer.
It is, therefore, the primary object of the present invention to provide a stereophonic microphone system which, in supplementing the sound field pickup technology of the past, generates an additional sound field information by using replicas of human ears which provide a characteristic multitude of ear resonances necessary for the perception of incidencies from all horizontal and vertical directions.